抄録
The acute effects of the selective alpha1-blocker, E-643 (Bunazosine), on experimental pulmonary hypertension (PH) caused by hypoxic pulmonary vasoconstriction (HPV) in mongrel dogs were examined .Ninety second ventilation with 5% O2 and 95% N2 was used for hypoxic stimulation .The effects of E-643 were evaluated at doses of 1, 5, 10, 20 and 50 μg/kg in this order until the systemic arterial mean pressure (SAm) had decreased by 20 mmHg when compared with the control value during room air ventilation. PaO2 and PaCO2 decreased by 64.6 ± 11.0 Torr and 2.4 ± 2.5 Torr, respectively, and the pH increased by 0.031 ± 0.012 during hypoxic ventilation. These blood gas changes affected during hypoxic stimulation were almost the same before E-643 administration. Progression of arterial blood hypoxemia due to E-643 administration during room air ventilation was not observed. SAm decreased by 8.0 ± 11.9 mmHg after E-643 administration, while left atrial mean pressure (LAm) and cardiac output (CO) did not change significantly. Prior to E-643 administration, mean pulmonary arterial pressure (PAm) and pulmonary vascular resistance (PVR) increased by 6.4 3.3 mmHg and 6.2 3.8 HRU, respectively, during the 90 sec hypoxic ventilation period. After E-643 administration, the increases in PAm and PVR were 3.9 1.7 mmHg and 3.3 2.3 HRU, respectively. The supression of increases in PAm and PVR was significant. The conclusion is that E-643, a selective alpha1-blocker, is effective at restraining HPV in the dog model.
